Model Reports
8 min readUpdated 11 Sep 2026
DVSA open data · 1,022 tests analysed
Mercedes-Benz Sl 2014: reliability & common MOT faults
151 first-attempt MOT failures were recorded on the 2014 Mercedes-Benz Sl in 2025. Figures are among first-attempt failed MOT tests, not among all tests.
First-attempt pass rate 85.2% across 1,022 tests in 2025. Nothing in this year's figures separates it from the Sls either side — no fuel gap, and no break in the model's own trend.
First-attempt pass
85.2%
of 1,022 first tests (2025)
First tests
1,022
test year 2025
Failed first attempts
151
failed first-attempt tests
MOT pass rates
First-attempt and official-style rates among class 4 first tests of the year.
First-attempt pass
85.2%
of 1,022 first tests (2025)
Official-style pass
85.8%
incl. same-day PRS fixes
First tests
1,022
class 4 · first MOT of the year
Typical age 11.0 yrs · median mileage 46,349 mi
vs 2024:
-1.1 pp first-attempt
Note:
Class 4 cars · first MOT of the year per vehicle · P/PRS/F outcomes (2025 data).
PRS (fixed at the station the same day) counts as a fail in the first-attempt rate.
Raw outcomes for this cohort — not adjusted for age, mileage, or peer mix.
MOT doesn't test engine or gearbox internals.
Wear patterns
Usage and mileage effects that often track road use rather than model design.
These patterns look like wear or usage effects rather than model-specific design faults.
Tyres, brake friction material, and alignment-related defects often track mileage and road use.
Pattern
Location
Failures
vs similar cars
Share of fails
Confidence
Tyres — Condition (rear)
Tyres > Condition
Rear
39
×4.2
25.8%
Wear
Tyres — Condition (front)
Tyres > Condition
Front
32
×2.8
21.2%
Wear
Note: These patterns are not treated as a model design fault in our common-faults ranking.
FAQs
Short answers about how to read this model-year guide.
Nothing in this year's figures separates it from the Sls either side — no fuel gap, and no break in the model's own trend. In 2025, 85.2% of 1,022 first MOTs on the 2014 Mercedes-Benz Sl passed first time (PRS — items fixed at the station the same day — counted as a fail). The official-style rate including PRS is 85.8%. Among 151 failed first-attempt MOT tests (test year 2025), we highlight MOT failure patterns that…
This page highlights MOT failure patterns for the 2014 Mercedes-Benz Sl (registration year) using UK DVSA open data for the selected test year. Patterns are compared with cars of a similar age and mileage. It is a buyer checklist from MOT defect statistics — not a full service history or manufacturer service-bulletin list.
No. MOT tests do not cover engine internals, gearboxes, or many electronic modules. Patterns here come from MOT defect statistics only and should not be read as engine or gearbox reliability scores.
About this data
How this page is built and what it can (and can't) say.
These figures come from UK MOT open data for this model year. We surface common failure patterns against similar cars — not a full reliability score, and not a pass/fail verdict on any individual vehicle.
20242025
What we include
UK Class 4 cars only. Normal MOT tests (not retests); first test per vehicle per calendar year; results pass, PRS, or fail.
Same-day repairs
PRS means the car failed items that were fixed at the test station and then passed the same day. We count PRS as a first-attempt fail in headline rates so same-day repairs do not hide problems.
How we compare
We compare this model year with other Class 4 cars of similar age and mileage in the same test year. This model family is left out of the peer group so the car is not measured against itself.
What this does not cover
MOTs do not cover engine internals, gearboxes, or many electronics — this is not a full reliability score.
Common faults come from MOT defect stats, not manufacturer TSBs or recalls.
Age and mileage matching reduces — but does not remove — differences in how cars were used and maintained.
We never invent pass rates, star scores, or ranks when those data marts are missing.